Autism is a developmental disorder defined by behavior and history indicating a particular constellation of deficits in abnormalities in reciprocal social interaction, communication and behaviors. It is believed to be heterogeneous in etiology as well as function and outcome. Variability is partly due to associations with a wide range of intellectual competence. There is also substantial variability across the three domains of social interaction, communication and repetitive behaviors, not accounted for by mental handicap. One still relatively unexplored source of variability are individual differences in basic cognitive processes, such as attention, that may affect the information taken in by individual children with autism, and hence, the knowledge, particularly about social functioning and communication, upon which more sophisticated processes are built. The aim of the project is to evaluate three hypotheses. The first is that autistic children have a particular deficit in use of rapidly presented visual cues to direct their attention. Second, deficits in rapid shifting of visual attention are expected to be characteristic of autism, but also of developmentally delayed children with exceptionally severe language delay. Third, nonautistic children are expected to have particular strengths in using social cues, specifically eye gaze and pointing, to direct their attention. Thus, nonautistic children are expected to be more responsive when they are invited to share attention to an object by an examiner's gaze than they are to attempts to direct their gaze without establishment of reciprocal looking. In contrast, it is hypothesized that autistic children lack or have less of this particular ability to interpret gaze than other children. Overall, the studies proposed are aimed at better understanding both joint attention and attentional shifts and orientation. Two methods are employed to compare the attentional responses, particularly directed gaze, of young autistic children to developmentally equivalent groups of language-impaired and mentally handicapped children and normally developing children. The first method consists of systematically varying the attentional demands and characteristics (e.g., contingent timing, object use) of tasks used to measure joint attention and requesting. The second method uses the movement of a laser beam as an analogue to directed gaze in order to create nonsocial tasks with similar attentional demands as the social joint attention contexts and then observes the children's responses. We hope to determine if the parameters of attention in nonsocial and social joint attention tasks and requests have similar effects and thus, address the question of the nature of deficits in attention as well as their relationship to deficits in social cognition.